1. Field of the Invention
The present invention relates to a printer with a cutter capable of appropriately cutting a recording sheet after printing on the recording sheet pulled out from a paper roll.
2. Description of the Related Art
Nowadays, a great number of various types of thermal printers, which performs printing by pressing a heated thermal head against a special recording sheet that changes color when heat is applied thereto, are provided. In particular, use is suitably made in printing of various labels, receipts, tickets, and the like because smooth character printing and colorful graphic printing are possible without using toner, ink, and the like.
As represented by the thermal printers, numerous printers with a cutter provided with a cutter mechanism for cutting the printed recording sheet are known. The cutter mechanism is normally set (auto cutter) to automatically cut the recording sheet when printing is terminated, and hence the cut recording sheet can be immediately used for a receipt, a ticket, and the like, as mentioned above.
The printer with a cutter is used by being incorporated in, for example, a cash register, a mobile terminal device, and the like.
The cutter mechanism is typically configured by a fixed blade and a movable blade that is slidable. When cutting the recording sheet, the movable blade is slid so as to ride on the upper surface of the fixed blade. Both the blades then sandwich and cut the recording sheet as if a pair of scissors.
The fixed blade is configured to have the root side supported by a hinge portion, and the cutting edge side to be swingable, and is biased to be pushed upward by a biasing portion such as a coil spring. Thus, when the movable blade slides, both the blades are brought into contact with each other at an appropriate contacting pressure. As a result, the recording sheet can be cut neatly.
However, the fixed blade and the movable blade often bite each other due to the jam of the recording sheet when cutting the recording sheet. For instance, the recording sheet enters and gets between the fixed blade and the movable blade, thereby regulating the swinging of the fixed blade and causing bite.
If such bite occurs, the printing needs to be interrupted and the recovery task needs to be immediately carried out. The bite needs to be recovered as fast as possible in order to promptly return to the printing task.
The configuration of a typical movable blade and fixed blade is described here with reference to the drawings.
As illustrating in FIG. 30A, a fixed blade 100 and a movable blade 101 are arranged on a downstream side of a conveying direction of the recording sheet with respect to a platen roller 102 for feeding a recording sheet P, and a print head 103 arranged so as to face the platen roller 102, for printing on the recording sheet P. The movable blade 101 is coupled to a motor (not shown) through an intermediation of a gear train mechanism 104 so as to slidably move closer to or move away from the fixed blade 100 by driving the motor. The gear train mechanism 104 is mainly configured by a worm gear 104a, coupled to a shaft of the motor, and a linear movement mechanism 104b including a plurality of gears that gears with the worm gear 104a, for linearly moving the movable blade 101 in accordance with the rotation of the gear.
In such configuration, as illustrated in FIG. 30B, the motor is driven to rotate the worm gear 104a to thereby cut the recording sheet P. The linear movement mechanism 104b converts the rotational force of the worm gear 104a to the force in the linear direction, and transmits the same to the movable blade 101. The movable blade 101 then moves towards the fixed blade 100, thereby making it possible to cut the recording sheet while holding it between the fixed blade 100 and the movable blade 101. The movable blade 101 returns to the original position (home position) by further rotating the motor after cutting the recording sheet P.
Using the worm gear 104a to slidably move the movable blade 101 is known as described in Patent Document JP 2006-075935 A.
If the bite of the fixed blade 100 and the movable blade 101 occurs during use, the worm gear 104a cannot rotate even if the motor is driven because the biting force is stronger. Thus, the worm gear 104a is forcibly rotated by hand to return the movable blade 101 to the home position. That is, the bite is resolved by forcibly slidably moving the movable blade 101 against the biting force.
A printer capable of resolving the bite between the fixed blade and the movable blade without requiring a special manual task is also known (see Patent Document JP 2004-237555 A).
This printer is briefly described with reference to the drawings.
As illustrated in FIG. 31A, the printer is mainly configured by a main unit 110 arranged in a casing (not shown), and a platen unit 111 arranged on an open/close cover (not shown) fixed to the casing in an openable/closable manner. The main unit 110 mainly incorporates a print head 112 for printing on the recording sheet P, a fixed blade 113 arranged on the downstream side in the conveying direction of the recording sheet with respect to the print head 112, and a first gear train 114 coupled to a motor (not shown).
The platen unit 111 mainly incorporates a platen roller 115 for feeding the recording sheet P, a movable blade 116 arranged on a downstream side in the conveying direction of the recording sheet with respect to the platen roller 115, and a second gear train 117 coupled to the movable blade 116, for slidably moving the movable blade 116. The platen unit 111 is combined with the main unit 110 when the open/close cover is closed, and is separated from the main unit 110 when the open/close cover is opened.
When the platen unit 111 and the main unit 110 are combined, the first gear train 114 and the second gear train 117 gear with each other, and the recording sheet P is sandwiched between the platen roller 115 and the print head 112, as illustrated in FIG. 31B. Thus, the print head 112 can perform printing, and, while feeding the recording sheet P with the platen roller 115, the movable blade 116 can be slidably moved towards the fixed blade 113 through an intermediation of the first gear train 114 and the second gear train 117 by the driving of the motor to thereby cut the recording sheet P.
The second gear train 117 is mainly configured by a gear 117a to be geared with the first gear train 114, and a pinion 117b to be geared with the gear 117a and a rack mechanism (not shown) fixed to the movable blade 116.
In particular, a biasing force for returning the movable blade 116 to the original position (home position) by a movable blade returning spring (not shown) acts on the pinion 117b. However, the pinion 117b is geared with the first gear train 114 when the open/close cover is closed, and hence it cannot rotate by the biasing force of the movable blade returning spring. That is, the pinion 117b can rotate by the biasing force of the movable blade returning spring to return the movable blade 116 to the home position only when the open/close cover is opened and the geared state of the pinion 117b and the first gear train 114 is released.
If bite occurs between the fixed blade 113 and the movable blade 116 while using the printer configured as described above, the open/close cover, which is closed with respect to the casing, is opened by hand. The platen unit 111 arranged on the open/close cover then separates from the main unit 110 on the casing side, as illustrated in FIG. 31C. The movable blade 116 then moves away from the fixed blade 113. Therefore, the bite of the fixed blade 113 and the movable blade 116 can be promptly resolved without requiring a special manual task. Further, the first gear train 114 and the second gear train 117 move apart, and hence the pinion 117b reverse-rotates by the movable blade returning spring and the movable blade 116 automatically returns to the home position, as illustrated in FIG. 31D.
Therefore, the bite of the fixed blade 113 and the movable blade 116 can be resolved with a simple operation of simply opening the open/close cover.
However, the following problems still exist in resolving the bite of the related art.
First, the method of returning the movable blade 101 to the home position by forcibly rotating the worm gear 104a by hand is very troublesome. Normally, when slidably moving the movable blade 101 using the rotational force of the motor, the rotation speed of the motor cannot be transmitted as is, and thus is reduced with use of the worm gear 104a. Thus, the motor only slightly rotates even if the worm gear 104a is rotated once. That is, the worm gear 104a needs to be rotated by the reduction ratio multiple in order to rotate the motor once. Therefore, the worm gear 104a needs to be rotated continuously for dozens of rotations so as to return the movable blade 101 to the home position. This is very troublesome, and the load on the operator is large. In addition, the recovery task take time, and the printing task cannot be promptly returned.
Regarding the method of resolving the bite by opening the open/close cover, the method is very simple, but the bite cannot be resolved in a situation in which the open/close cover itself cannot be opened. That is, there is a risk that the platen unit 111 gets locked to the main unit 110 or the casing depending on the jam of the recording sheet P, and in this case, the open/close cover itself cannot be opened. Thus, the movable blade 116 and the fixed blade 113 obviously cannot be spaced apart, and the bite cannot be resolved.